Nowadays it is common practice to install hemming tools into presses or stroke racks. For the various hemming stages, two tools and thus two presses are needed or one of the two foldings is executed through a complicated slide or flap technique.
From DE 44 18684 A1 it is known to provide a method for joining of sheet metals by means of bordering. The parts to be joined are machined in a press in at least one pre-bordering and finish bordering. A pre-bordering of the parts during a first transformation phase is effected by means of a prebordering edge of a mobile slide. The slide then moves radially towards the outside. A second bordering tool with a bordering edge during a second transformation phase executes a finish bordering of the parts to be joined together. Both the loading of tools in the press with the parts to be machined and the take-out of machined sheet metals are relatively expensive according to this method.
U.S. Pat. No. 5,150,508 describes a generic bordering device for two sheet metals with a highstanding flange lying one above each other, wherein a ram with a superimposed hemming bed in a base rack presses the sheet metals to be hemmed consecutively against the hemming jaws of the pre-hemming and finish hemming tools. In the process the hemming tools are moved radially from outside to inside consecutively into the hemming position and the hemming bed is adjusted in height for the individual hemming procedures. Here, too, the change of tools is very expensive.